USACOTrainning.Healthy Holsteins
这个题有意思，刚开始由于不是很理解题意还以为是DP，后来清楚并发现给的Feed的数量很少2^15次方全部弄出来就行了。但关于去最先序列的答案，用位运算^h和&搞定。t&(-t)，取最低位的1还真好使，还有^运算，神奇。
1
#include
<
iostream
>
2
#include
<
string
>
3
#include
<
algorithm
>
4
#include
<
string
.h
>
5
#include
<
vector
>
6
#include
<
math.h
>
7
#include
<
time.h
>
8
#include
<
queue
>
9
#include
<
set
>
10
using
namespace
std;
11
12
const
int
MAXV
=
30
;
13
const
int
MAXN
=
20
;
14
15
int
n, m, ans, ansState;
16
int
all[MAXV];
17
int
sub[MAXN][MAXV];
18
19
bool
check(
int
x)
20
{
21
int
i
=
0
;
22
int
t[MAXV];
23
memset(t,
0
,
sizeof
(t));
24
while
(x)
25
{
26
if
(x
&
1
)
27
{
28
for
(
int
j
=
0
; j
<
m; j
++
)
29
{
30
t[j]
+=
sub[i][j];
31
}
32
}
33
i
++
;
34
x
>>=
1
;
35
}
36
for
(i
=
0
; i
<
m; i
++
)
37
{
38
if
(t[i]
<
all[i])
return
false
;
39
}
40
return
true
;
41
}
42
43
int
getNum(
int
x)
44
{
45
int
res
=
0
;
46
while
(x)
47
{
48
if
(x
&
1
) res
++
;
49
x
>>=
1
;
50
}
51
return
res;
52
}
53
54
bool
checkCMP(
int
x,
int
y)
55
{
56
int
z
=
x
^
y;
57
z
=
z
&
(
-
z);
58
if
(z
&
x)
return
true
;
59
else
return
false
;
60
}
61
62
void
go()
63
{
64
ans
=
100
;
65
for
(
int
i
=
0
; i
<
(
1
<<
n); i
++
)
66
{
67
if
(check(i))
68
{
69
int
num
=
getNum(i);
70
if
(num
<
ans)
71
{
72
ans
=
num;
73
ansState
=
i;
74
}
75
else
if
(num
==
ans)
76
{
77
if
(checkCMP(i, ansState))
78
{
79
ansState
=
i;
80
}
81
}
82
}
83
}
84
printf(
"
%d
"
, ans);
85
for
(
int
i
=
0
; i
<
20
; i
++
)
86
{
87
if
(ansState
&
(
1
<<
i)) printf(
"
%d
"
, i
+
1
);
88
}
89
printf(
"
\n
"
);
90
}
91
92
int
main()
93
{
94
freopen(
"
holstein.in
"
,
"
r
"
, stdin);
95
freopen(
"
holstein.out
"
,
"
w
"
, stdout);
96
97
scanf(
"
%d
"
,
&
m);
98
for
(
int
i
=
0
; i
<
m; i
++
) scanf(
"
%d
"
,
&
all[i]);
99
scanf(
"
%d
"
,
&
n);
100
for
(
int
i
=
0
; i
<
n; i
++
)
101
{
102
for
(
int
j
=
0
; j
<
m; j
++
)
103
scanf(
"
%d
"
,
&
sub[i][j]);
104
}
105
go();
106
}